JP7464520B2 - Composition for high strength sidewalls - Google Patents

Description

The present invention relates to rubber compositions comprising natural rubber, polybutadiene rubber, and polyolefins, methods for producing the same, and articles prepared therefrom.

A pneumatic run-flat tire is a tire that can be used in an uninflated state (complete loss of air pressure other than that of the surrounding air pressure). Vehicles equipped with such tires can continue to be driven after a loss of tire pressure, such as that caused by a puncture or valve failure. This type of tire is also called an extended mobility tire (EMT).

A key component of many run-flat tires is the stiff sidewall (rubber) insert, which supports most of the vehicle's weight on the tire after air pressure loss and allows driving even with zero tire air pressure. Conventional sidewall inserts for run-flat tires utilize natural rubber (NR) and polybutadiene rubber (BR) as the base polymer and carbon black as the filler. Typically, a filler type or load is used to increase the material stiffness of the sidewall insert. In the vehicle industry, the trend is to reduce the weight of the components and therefore the overall weight of the vehicle.

There is a need for polymeric compounds that can be used to form products, such as sidewall inserts, that have higher levels of hardness and modulus, as well as enhanced material stiffness, while at the same time maintaining or reducing the density of the material as compared to the density of products, such as sidewall inserts, formed from conventional rubber compounds. These needs and several others are met by the following inventions.

The present invention relates to a composition comprising at least the following:
A) natural rubber having a density of 0.90 to 0.93 g/ ^cm3 and a Mooney viscosity (ML(1+4)@100°C) of 50 to 90;
B) a butadiene rubber having a density of 0.90 to 0.93 g/ ^cm3 and a Mooney viscosity (ML(1+4)@100°C) of 40 to 110;
C)
i) ethylene/α-olefin copolymers having a density of 0.870 to 0.902 and a Mooney viscosity (ML(1+4)@121°C) of 2 to 23;
ii) an ethylene/α-olefin multi-block copolymer having a density from 0.866 to 0.887, a Mooney viscosity (ML(1+4)@121°C) from 4 to 20, or iii) at least one ethylene-based polymer selected from i) and ii).

Mooney viscosity is the viscosity of the base polymer (the calculated viscosity of a neat polymer versus a polymer containing a filler such as carbon black).

In one embodiment, the at least one ethylene-based polymer is an ethylene/α-olefin copolymer having a melt index (I ₂ ) from 1 to 30. In one embodiment, the at least one ethylene-based polymer is an ethylene/α-olefin multiblock copolymer having a melt index (I ₂ ) from 1 to 15.

The present invention also provides a method for producing a polymer composition, the method comprising mixing together at least natural rubber, butadiene rubber, and an ethylene/α-olefin copolymer, and/or an ethylene/α-olefin multiblock copolymer, and optionally at least one oil and/or a filler.

The present invention further provides an article comprising at least one component formed from the composition. In one embodiment, the article is an automobile part. In one embodiment, the article is a tire or a tire sidewall insert.

The incorporation of ethylene-based polyolefin elastomers (POE) and/or olefin block copolymers (OBC) into natural rubber/butadiene rubber formulations has been found to provide compositions with unexpectedly enhanced mechanical properties while maintaining the density of the base rubber, which can be used to create slimmer profiles in sidewall inserts for significant weight reduction in run-flat tires without sacrificing tire durability.

In particular, the present invention relates to a composition comprising at least the following:
A) natural rubber having a density of 0.90 to 0.93 g/ ^cm3 and a Mooney viscosity (ML(1+4)@100°C) of 50 to 90;
B) a butadiene rubber having a density of 0.90 to 0.93 g/ ^cm3 and a Mooney viscosity (ML(1+4)@100°C) of 40 to 110;
C)
i) ethylene/α-olefin copolymers having a density of 0.870 to 0.902 and a Mooney viscosity (ML(1+4)@121°C) of 2 to 23;
ii) an ethylene/α-olefin multi-block copolymer having a density from 0.866 to 0.887 and a Mooney viscosity (ML(1+4)@121°C) from 4 to 20; or iii) at least one ethylene-based polymer selected from a combination of i) and ii).

Mooney viscosity is the viscosity of the base polymer (the calculated viscosity of a neat polymer versus a polymer containing a filler such as carbon black).

In one embodiment, the ratio of density of component C to component A is 0.94 to 1.00.

In one embodiment, the ratio of the Mooney viscosity of component A to the melt index of component C is 12 to 60.

In one embodiment, component C is i) an ethylene/α-olefin copolymer, and the weight ratio of component C to component A is 0.22 to 0.64.

In one embodiment, component C is ii) an ethylene/α-olefin multiblock copolymer, and the weight ratio of component C to component A is 0.20 to 0.50.

In one embodiment, component C) is an ethylene/α-olefin copolymer having i) a density of 0.870 to 0.902 and a Mooney viscosity (ML(1+4)@121°C) of 2 to 23.

In one embodiment, component C) is an ethylene/α-olefin multiblock copolymer having ii) a density of 0.866-0.887 and a Mooney viscosity (ML(1+4)@121°C) of 4-20.

In one embodiment, component C) includes both i) an ethylene/α-olefin copolymer having a density of 0.870-0.902 and a Mooney viscosity (ML(1+4)@121°C) of 2-23, and ii) an ethylene/α-olefin multiblock copolymer having a density of 0.866-0.887 and a Mooney viscosity (ML(1+4)@121°C) of 4-20.

In one embodiment, the natural rubber is polyisoprene. In one embodiment, the polyisoprene is natural or synthetic polyisoprene, preferably natural polyisoprene. In another embodiment, the polyisoprene is natural cis-1,4-polyisoprene. In another embodiment, the polyisoprene is synthetic cis-1,4-polyisoprene. In one embodiment, the natural rubber has a density of 0.90 to 0.93 g/ ^cm3 . In one embodiment, the polyisoprene has a Mooney viscosity, ML(1+4)@100°C, of 50 to 90, or 50 to 80, or 55 to 75, or 60 to 70. In another embodiment, the polyisoprene is derived from a non-granular bale form.

In one embodiment, the butadiene rubber has a density of 0.90 to 0.93 g/ ^cm3 . In one embodiment, the butadiene rubber has a Mooney viscosity (ML(1+4)@100°C) of 40 to 110, or 40 to 80, or 40 to 60. In one embodiment, the butadiene rubber is polybutadiene. In another embodiment, the polybutadiene comprises a high cis content, greater than 97 percent, based on the total weight of polymerizable monomers.

In one embodiment, the at least one ethylene-based polymer is an ethylene/α-olefin copolymer. In one embodiment, the ethylene/α-olefin copolymer has a Mooney viscosity (ML(1+4)@121° C.) from 2 to 23, or from 4 to 23, or from 8 to 23. Mooney viscosity is the viscosity of the base polymer (the calculated viscosity of the neat polymer relative to a polymer containing a filler such as carbon black). In one embodiment, the at least one ethylene-based polymer is an ethylene/α-olefin copolymer having a melt index (I ₂ ) from 1 to 30 g/10 min. In a further embodiment, the ethylene/α-olefin copolymer is an ethylene/octene copolymer.

In another embodiment, the at least one ethylene-based polymer is an ethylene/α-olefin multi-block copolymer. In one embodiment, the ethylene/α-olefin multi-block copolymer has a Mooney viscosity (ML(1+4)@121° C.) from 4 to 20, or from 8 to 20, or from 12 to 20. Mooney viscosity is the viscosity of the base polymer (the calculated viscosity of the neat polymer relative to a polymer containing a filler such as carbon black). In one embodiment, the at least one ethylene-based polymer is an ethylene/α-olefin multi-block copolymer having a melt index (I ₂ ) from 1 to 15 g/10 min. In a further embodiment, the ethylene/α-olefin multi-block copolymer is an ethylene/octene multi-block copolymer.

In another embodiment, the at least one ethylene-based polymer is a blend of an ethylene/α-olefin copolymer and an ethylene/α-olefin multi-block copolymer. In one embodiment, the blend of the ethylene/α-olefin copolymer and the ethylene/α-olefin multi-block copolymer has a Mooney viscosity (ML(1+4)@121° C.) from 3 to 22, or from 5 to 22, or from 8 to 22. Mooney viscosity is the viscosity of the polymer blend (calculated viscosity of the neat polymer blend versus the polymer blend containing a filler such as carbon black). In one embodiment, the at least one ethylene-based polymer is a blend of an ethylene/α-olefin copolymer and an ethylene/α-olefin multi-block copolymer, the mixture having a melt index (I ₂ ) from 1 to 29 g/10 min. In a further embodiment, the ethylene-based polymer is a blend of an ethylene/octene copolymer and an ethylene/octene multi-block copolymer.

In one embodiment, the natural rubber is present in an amount of 30 wt%, or 35 wt%, or 40 wt% or more, based on the total weight of the composition. In another embodiment, the natural rubber is present in an amount of less than 55 wt%, or 50 wt%, or 45 wt%, based on the total weight of the composition. In one embodiment, the natural rubber is present in an amount of 30-55 wt%, or 35-50 wt%, or 40-45 wt%, based on the total weight of the composition.

In one embodiment, the butadiene rubber is present in an amount of 30 wt%, or 35 wt%, or 40 wt% or more, based on the total weight of the composition. In another embodiment, the butadiene rubber is present in an amount up to 55 wt%, or 50 wt%, or 45 wt%, based on the total weight of the composition. In one embodiment, the butadiene rubber is present in an amount from 30 to 55 wt%, or from 35 to 50 wt%, or from 40 to 45 wt%, based on the total weight of the composition.

In one embodiment, the at least one ethylene-based polymer is present in a total amount of 5 weight percent or more, or 10 weight percent or more, based on the total weight of the composition. In another embodiment, the at least one ethylene-based polymer is present in a total amount of up to 30, or up to 25, or up to 20 weight percent, based on the total weight of the composition. In another embodiment, the at least one ethylene-based polymer is present in a total amount of 5 to 30 weight percent, based on the total weight of the composition.

In one embodiment, the at least one ethylene-based polymer is a blend of an ethylene/α-olefin copolymer and an ethylene/α-olefin multi-block copolymer in a ratio of 5:95 to 95:5 (w/w). In one embodiment, the composition comprises, based on the total weight of the composition, A) 30 to 55 weight percent natural rubber, B) 30 to 55 weight percent butadiene rubber, and C) 5 to 30 weight percent of at least one ethylene-based polymer selected from an ethylene/α-olefin copolymer and/or an ethylene/α-olefin multi-block copolymer.

In one embodiment, the composition comprises a total amount of components A, B and C of at least 80, or at least 85, or at least 90, or at least 95 wt. %, based on the total weight of the composition.

In one embodiment, the composition has a Mooney viscosity (ML(1+4)@125°C) of 35 to 90, or 40 to 85, or 42 to 80, or 45 to 70.

In one embodiment, the composition has a density from 1.04 to 1.15, or from 1.05 to 1.13, or from 1.06 to 1.10 g/cm ³ .

In one embodiment, the composition has a Shore A hardness of 65 to 90, or 70 to 80.

In one embodiment, the composition has a thermogenic delta temperature of 50°C or less, or 40°C or less, or 30°C or less, or between 20 and 50°C.

In one embodiment, the composition comprises less than 1 weight percent, or less than 0.5 weight percent, or less than 0.1 weight percent, or zero (0) weight percent ethylene/alpha-olefin/diene (EAODM) interpolymer (e.g., ethylene/propylene/diene (EPDM)).

In one embodiment, the composition further comprises at least one filler. In one embodiment, the filler is carbon black. In another embodiment, the composition comprises 15-40 wt.%, or 20-35 wt.%, or 35-30 wt.% carbon black, based on the total weight of the composition.

In one embodiment, the composition further comprises one or more additives. In one embodiment, the additives are selected from plasticizers, process oils, vulcanization accelerators, crosslinking agents, antioxidants, antiozonants, peptizers, activators, fatty acids, accelerators, tackifiers, homogenizers, pigments, colorants, flame retardants, UV stabilizers, fungicides, slip agents, and the like, and combinations thereof.

In a further embodiment, the composition further comprises at least one processing oil. In one embodiment, the processing oil is selected from the group consisting of aromatic oils, paraffinic oils, and naphthenic oils.

The compositions of the present invention may include a combination of two or more embodiments described herein.

The present invention further provides a crosslinked composition formed from the composition, hi one embodiment, the crosslinked composition has a density of 1.04 to 1.15, or 1.05 to 1.13 g/ ^cm2 .

The present invention further provides an article comprising at least one component formed from the composition. In one embodiment, the article is an automobile part. In another embodiment, the article is a tire or a tire insert.

An article of the invention may include a combination of two or more of the embodiments described herein.

The present invention further provides a method of making a polymer composition. In one embodiment, the method includes mixing together at least one ethylene-based polymer selected from natural rubber, butadiene rubber, and ethylene/α-olefin copolymers, and/or ethylene/α-olefin multiblock copolymers, and, optionally, at least one processing oil and/or filler.

In one embodiment, the method comprises the steps of: A) mixing a natural rubber having a density of 0.90 to 0.93 g/ ^cm3 and a Mooney viscosity (ML(1+4)@100°C) of 50 to 90; and B) mixing a natural rubber having a density of 0.90 to 0.93 g/cm3 and a Mooney viscosity (ML(1+4)@100°C) of 50 to 90. The method includes blending together: C) at least ^one ethylene-based polymer selected from: i) an ethylene/α-olefin copolymer having a density of 0.870-0.902 and a Mooney viscosity (ML(1+4)@121°C) of 2-23; ii) an ethylene/α-olefin multiblock copolymer having a density of 0.866-0.887 and a Mooney viscosity (ML(1+4)@121°C) of 4-20; or iii) a combination of i) and ii); and D) optionally at least one processing oil and/or filler. The Mooney viscosity is the viscosity of the neat polymer (calculated viscosity of the neat polymer relative to a polymer containing a filler such as carbon black). In one embodiment, the ethylene-based polymer is an ethylene/α-olefin copolymer having a melt index (I ₂ ) of 1-30 g/10 min. In one embodiment, the ethylene-based polymer is an ethylene/α-olefin multiblock polymer having a melt index (I ₂ ) from 1 to 15 g/10 min. In one embodiment, the ethylene-based polymer is a blend of an ethylene/α-olefin copolymer and an ethylene/α-olefin multiblock polymer, where the ethylene-based polymer blend has a melt index (I ₂ ) from 1 to 29 g/10 min.

The methods of the present invention may include a combination of two or more of the embodiments described herein.

Natural Rubber In one embodiment, the composition comprises natural rubber. In one embodiment, the natural rubber is polyisoprene. In one embodiment, the polyisoprene is natural polyisoprene. In one embodiment, the polyisoprene is synthetic polyisoprene. In a preferred embodiment, the polyisoprene is natural polyisoprene. Suitable polyisoprenes include, but are not limited to, natural cis-1,4-polyisoprene, synthetic cis-1,4-polyisoprene, high vinyl 3,4-polyisoprene, and 3,4-polyisoprene.

In one embodiment, the polyisoprene has a density of at least 0.90, or at least 0.91, or at least 0.92 g/cm ³ , up to 0.93 g/cm ³ .

In one embodiment, the polyisoprene has a Mooney viscosity (ML(1+4)@100°C) of 50 to 90, preferably 50 to 80, more preferably 60 to 70. The Mooney viscosity is the viscosity of the base polymer (the calculated viscosity of the neat polymer versus a polymer containing a filler such as carbon black).

In another embodiment, the polyisoprene is derived from a non-granular veiled form.

Suitable examples of polyisoprene include the following technical grades: STR-20 (TongThai Technical Rubber Co., Ltd., Thailand), SMR (Standard Malaysian Rubber), e.g., SRM 5 and SMR 20; TSR (Technical Grade Rubber) and RSS (Ribbed Smoked Sheet).

Butadiene Rubber In one embodiment, the butadiene rubber is polybutadiene. Suitable polybutadienes include, but are not limited to, natural cis-1,4-polybutadiene, trans-1,4-polybutadiene, vinyl-1,2-polybutadiene, copolymers of styrene and butadiene, copolymers of isoprene and butadiene, and interpolymers of styrene, isoprene, and butadiene.

In one embodiment, the polybutadiene contains a high cis content of greater than 97%, based on the total weight of polymerizable monomers.

In one embodiment, the polybutadiene has a density of at least 0.90, or at least 0.91, or at least 0.92 g/cm ³ , up to 0.93 g/cm ³ .

In one embodiment, the polybutadiene has a Mooney viscosity (ML(1+4)@100°C) of 40 to 110, preferably 40 to 80, more preferably 40 to 60. The Mooney viscosity is the viscosity of the base polymer (the calculated viscosity of the neat polymer versus a polymer containing a filler such as carbon black).

Examples of suitable polybutadienes include KBR 01 from Kumho Petrochemical (Korea), EUROPRENE NEOCIS BR 40 from Polimeri Europe, and BUNA CB 24 Lanxess.

Ethylene/α-Olefin Copolymer "Ethylene/alpha-olefin copolymer," as used herein, refers to a polymer comprising repeat units derived from ethylene and one α-olefin comonomer.

The ethylene/α-olefin copolymer comprises more than 50 mol% of units derived from ethylene, e.g., 60 mol% or more, 70 mol% or more, 80 mol% or more, or 90 mol% or more. The ethylene/α-olefin copolymer further comprises less than 30 mol% of units derived from one or more α-olefin comonomers, e.g., 25 mol% or less, or 20 mol% or less, 15 mol% or less, or 10 mol% or less. In one embodiment, the ethylene/α-olefin copolymer comprises more than 50 mol% of units derived from ethylene and less than 30 mol% of units derived from one or more α-olefin comonomers.

The α-olefins can be either aliphatic or aromatic and can include vinyl unsaturated or cyclic compounds such as styrene, p-methylstyrene, cyclobutene, cyclopentene, norbornene. The α-olefin comonomers are preferably C ₃ -C ₂₀ aliphatic compounds, preferably C ₃ -C ₁₀ aliphatic compounds. Exemplary unsaturated α-olefin comonomers include, but are not limited to, 4-vinylcyclohexane, vinylcyclohexane, and C 3 -C 10 aliphatic α-olefins including propylene, isobutylene, 1-butene, 1-pentene, 1-hexene, 3 _- methyl-1-pentene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-decene, and 1-dodecene. In another embodiment, the α-olefin comonomer is selected from the group consisting of propylene, 1-butene, 1 _- hexane, and 1-octene.

Ethylene/α-olefin copolymers may be heterogeneously branched or homogeneously branched. Heterogeneously branched copolymers may be produced by Ziegler-Natta type catalysts and contain a heterogeneous distribution of comonomers among the molecules of the copolymer. Homogeneously branched copolymers may be produced, for example, by single-site catalyst systems and contain a substantially uniform distribution of comonomers among the molecules of the copolymer.

In embodiments herein, the ethylene/α-olefin copolymers have a density in the range of 0.870 to 0.902, or 0.87 to 0.89, or 0.87 to 0.88 g/cm ^3. All individual values and subranges from 0.870 to 0.902 g/cm ³ are included and disclosed herein. The densities disclosed herein for the ethylene/α-olefin copolymers are determined according to ASTM D-792.

In further embodiments, the ethylene/α-olefin copolymer has a Mooney viscosity (ML(1+4)@121°C) of at least 2, or at least 4, or at least 8, up to 23. The Mooney viscosity of the ethylene/α-olefin copolymer is the viscosity of the base polymer (the calculated viscosity of the neat polymer relative to a polymer containing a filler such as carbon black).

In further embodiments, the ethylene/α-olefin copolymers have a melt index ( _I2 ) from 1 to 30, or from 1 to 15, or from 1 to 10 g/10 min (190°C/2.16 kg). All individual values and subranges from 1 to 30 g/10 min are included and disclosed herein. The melt index, or _I2 , of the ethylene/α-olefin copolymers is determined according to ASTM D1238 at 190°C, 2.16 kg.

Commercial examples of ethylene/α-olefin copolymers (elastomers) suitable for use herein include homogeneously branched, substantially linear ethylene/α-olefin polymers, such as ENGAGE™ polyolefin elastomers (e.g., ENGAGE™ 8003, 8400, 8450 and 8480 polyolefin elastomers) available from The Dow Chemical Company, Midland, Michigan USA, and AFFINITY™ polyolefin plastomers, available from ExxonMobil Chemical Company, Houston, Texas. These include EXCEED™ and EXACT™ polymers available from USA, and TAFMER™ polymers available from Mitsui Chemical Co.

Any conventional ethylene (co)polymerization reaction process may be used to produce the ethylene/α-olefin copolymers. Typical conventional ethylene (co)polymerization reaction processes include, but are not limited to, slurry phase polymerization processes, solution phase polymerization processes, and/or combinations thereof, using one or more conventional reactors, such as loop reactors, stirred tank reactors, batch reactors in parallel, in series, and/or any combination thereof. Suitable methods for forming ethylene/α-olefin copolymers can be found in U.S. Pat. No. 4,547,475, which is incorporated herein by reference for that purpose.

In some embodiments, ethylene/α-olefin copolymers may be produced using a liquid phase polymerization process. Such processes may occur in a well-stirred reactor, such as a loop reactor or a spherical reactor, at temperatures of about 150° C. to about 300° C., or about 180° C. to about 200° C., and at pressures of about 30 to about 1000 psi, or about 600 to about 850 psi. The residence time in such processes is about 2 to about 20 minutes, or about 3 to about 10 minutes. Ethylene, solvent, catalyst, and optionally one or more comonomers are continuously fed to the reactor. Exemplary catalysts in these embodiments include, but are not limited to, Ziegler-Natta catalysts. Exemplary solvents include, but are not limited to, isoparaffins. For example, such solvents are commercially available under the name ISOPAR E (ExxonMobil Chemical Co., Houston, Texas USA). The resulting mixture of ethylene/α-olefin copolymer and solvent is then removed from the reactor and the polymer is isolated. The solvent is typically recovered via a solvent recovery unit, i.e., a heat exchanger and a gas-liquid separator drum, and recycled to the polymerization system.

An exemplary multicomponent catalyst system can include a Ziegler-Natta catalyst composition that includes magnesium- and titanium-containing catalyst precursors, and cocatalysts (reducing agents) that include aluminum compounds, compounds of lithium, sodium, and potassium, alkaline earth metals, and compounds of other earth metals.

Other catalyst systems that may be used to form ethylene/α-olefin copolymers include metallocene catalysts, constrained geometry catalysts ("CGC catalysts"), such as those disclosed in U.S. Pat. No. 5,272,236, U.S. Pat. No. 5,278,272, U.S. Pat. No. 6,812,289, and WO 93/08221, as well as metallocene "bisCP catalysts."

The ethylene/α-olefin copolymer may include a combination of two or more embodiments described herein.

Ethylene/α-Olefin Multiblock Copolymers The term "ethylene/α-olefin copolymer,""olefin block copolymer," or "OBC," as used herein, refers to an ethylene/α-olefin multiblock copolymer, comprising in polymerized form ethylene and one or more copolymerizable α-olefin comonomers characterized by multiple blocks or segments of two or more polymerized monomer units differing in chemical or physical properties. The terms "interpolymer" and "copolymer" are used interchangeably herein for the term ethylene/α-olefin block copolymer, and similar terms discussed in this paragraph. When referring to the amount of "ethylene" or "comonomer" in a copolymer, it is understood that this refers to the polymerized units thereof. In some embodiments, a multiblock copolymer can be represented by the following formula:
(AB) _n
In the formula, n is at least 1, and preferably is an integer greater than 1, for example, 2, 3, 4, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, or more, and "A" represents a hard block or segment, and "B" represents a soft block or segment. Preferably, the A and B blocks are linked in a substantially linear fashion, as opposed to a substantially branched or substantially star-shaped fashion. In other embodiments, the A and B blocks are randomly distributed along the polymer chain. In other words, block copolymers do not usually have the following structure:
AAA-AAA-BBB-BB.

In yet other embodiments, the block copolymer does not generally have a third type of block that includes a different comonomer. In still other embodiments, each of blocks A and B has monomers or comonomers substantially randomly distributed within the block. In other words, neither block A nor block B includes two or more compositionally distinct subsegments (or subblocks), such as tip segments, that have a substantially different composition than the remainder of the block.

In one embodiment, ethylene preferably comprises the majority mole fraction of the whole block copolymer, i.e., ethylene comprises at least 50 mole percent (mol%) of the whole polymer. More preferably, ethylene comprises at least 60, at least 70, or at least 80 mol%, with a substantial remainder of the whole polymer comprising at least one other comonomer, preferably an α-olefin having three or more carbon atoms. In some embodiments, the olefin block copolymer may comprise 50-90 mol% ethylene, preferably 60-85 mol%, more preferably 65-80 mol%. For many ethylene/octene block copolymers, preferred compositions include an ethylene content of greater than 80 mol% of the whole polymer, and an octene content of 10-15 mol%, preferably 15-20 mol%, of the whole polymer.

Ethylene/α-olefin block copolymers contain various amounts of "hard" and "soft" segments. "Hard" segments are blocks of polymerized units in which ethylene is present in an amount greater than 95%, or greater than 98%, up to 100% by weight based on the weight of the polymer. In other words, the comonomer content (content of monomers other than ethylene) in the hard segments can be less than 5, or less than 2% by weight based on the weight of the polymer, and as low as zero. In some embodiments, the hard segments contain all or substantially all units derived from ethylene. "Soft" segments are blocks of polymerized units in which the comonomer content (content of monomers other than ethylene) is greater than 5%, or greater than 8%, or greater than 10%, or greater than 15% by weight based on the weight of the polymer. In some embodiments, the comonomer content in the soft segments can be greater than 20%, 25%, 30%, 35%, 40%, 45%, 50%, or 60% by weight, and can be up to 100% by weight.

The soft segments can be present in the OBC at 1-99% by weight of the total weight of the OBC, or at 5-95%, 10-90%, 15-85%, 20-80%, 25-75%, 30-70%, 35-65%, 40-60%, or 45-55% by weight of the total weight of the OBC. Conversely, the hard segments can be present within similar ranges. The soft segment weight percentage and the hard segment weight percentage can be calculated based on data obtained from DSC or NMR. Such methods and calculations are disclosed, for example, in U.S. Pat. No. 7,608,668. Specifically, the hard and soft segment weight percentages and comonomer content can be determined as described in U.S. Pat. No. 7,608,668, columns 57-63, which are incorporated herein by reference for that purpose.

Ethylene/α-olefin block copolymers are preferably polymers containing two or more chemically distinct regions or segments (referred to as "blocks") linked in a linear fashion, i.e., polymers containing chemically distinct units linked end-to-end with respect to polymerized ethylenic functional groups, rather than in a pendant or grafted fashion. In one embodiment, the blocks differ in the amount or type of comonomer incorporated, density, crystallinity, crystal size resulting from polymers of such composition, type or degree of stereoregularity (isotactic or syndiotactic), regioregularity or regioirregularity, amount of branching (including long chain branching or hyperbranching), homogeneity, or any other chemical or physical property. Compared to prior art block interpolymers, including interpolymers produced by sequential monomer addition, flow catalyst, or anionic polymerization techniques, the OBCs of the present invention are characterized, in one embodiment, by a unique distribution of both polymer polydispersity (PDI or Mw/Mn or MWD), block length distribution, and/or block number distribution, due to the effect of the shuttle agent(s) in combination with the multiple catalysts used in their preparation.

In one embodiment, the OBC is produced in a continuous process and has a polydispersity index, PDI (or MWD), of 1.7 to 3.5, or 1.8 to 3, or 1.8 to 2.5, or 1.8 to 2.2. When produced in a batch or semi-batch process, the OBC has a PDI of 1.0 to 3.5, or 1.3 to 3, or 1.4 to 2.5, or 1.4 to 2.

Additionally, ethylene/α-olefin block copolymers have PDIs that fit a Schultz-Flory distribution rather than a Poisson distribution. OBCs have both a polydisperse block distribution as well as a polydisperse distribution of block sizes. This results in the formation of polymer products with improved and identifiable physical properties. The theoretical advantages of a polydisperse block distribution have been previously modeled and discussed in Potemkin, Physical Review E (1998) 57(6), pp. 6902-6912 and Dobrynin, J. Chem. Phvs. (1997) 107(21), pp. 9234-9238.

In one embodiment, the ethylene/α-olefin block copolymers have a robust distribution of block lengths. In one embodiment, the ethylene/α-olefin block copolymers are defined as having at least one of the following properties A through E:
(A) a Mw/Mn of 1.7 to 3.5, at least one melting point Tm in degrees Celsius, and a density d in grams per cubic centimeter, where the numerical values of Tm and d correspond to the following relationship:
and/or (B) is characterized ^by a Mw/Mn of 1.7 to 3.5, a heat of fusion ΔH in J/g, and a delta magnitude ΔT in degrees Celsius, defined as the temperature difference between the highest DSC peak and the highest crystallization temperature analysis fraction ("CRYSTAF") peak, where the numerical values of ΔT and ΔH have the following relationship:
For ΔH greater than zero and up to 130 J/g, ΔT>−0.1299(ΔH)+62.81;
For ΔH greater than 130 J/g, ΔT≧48° C.
wherein the CRYSTAF peak is determined using at least 5 percent of the cumulative polymer, and when less than 5 percent of the polymer has an identifiable CRYSTAF peak, the CRYSTAF temperature is 30° C.; and/or (C) the elastic recovery Re at 300% strain and one cycle, and the density d in grams per cubic centimeter, measured on a compression molded film of the ethylene/α-olefin interpolymer, wherein the numerical values of Re and d satisfy the following relationship when the ethylene/α-olefin interpolymer is substantially free of a crosslinked phase:
and/or (D) having a molecular fraction that elutes between 40° C. and 130° C. when fractionated using TREF, the fraction being characterized by a molar comonomer content in an amount equal to or greater than (−0.2013)T+20.07, more preferably equal to or greater than (−0.2013)T+21.07, where T is the numerical value of the peak elution temperature of the TREF fraction, measured in ° C.; and/or
(E) has a storage modulus at 25° C., G'(25° C.), and a storage modulus at 100° C., G'(100° C.), where the ratio of G'(25° C.) to G'(100° C.) is in the range of 1:1 to 9:1.

In one embodiment, the ethylene/α-olefin block copolymer may further comprise:
(F) a molecular fraction which, when fractionated using TREF, elutes between 40° C. and 130° C., the fraction being characterized by having a block index of at least 0.5 to 1 and a molecular weight distribution Mw/Mn greater than 1.3; and/or (G) an average block index greater than zero and up to 1.0 and a molecular weight distribution Mw/Mn greater than 1.3.

It is understood that the ethylene/α-olefin block copolymer can have one, some, all, or any combination of properties (A)-(G). Block index can be determined as detailed in U.S. Pat. No. 7,608,668, which is incorporated herein by reference for that purpose. Analytical methods for determining properties (A)-(G) are disclosed, for example, in column 31, line 26 to column 35, line 44 of U.S. Pat. No. 7,608,668, which is incorporated herein by reference for that purpose.

Suitable monomers for use in preparing the OBC include ethylene and one or more addition polymerizable monomers other than ethylene. Examples of suitable comonomers include C 3-30 , preferably C 3-20 linear or branched α-olefins such as propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene; C _3-30 , preferably C _3-20 linear or branched α-olefins such as cyclopentene, cycloheptene, norbornene, 5-methyl-2-norbornene, tetracyclododecene, and 2-methyl-1,4,5,8-dimethano-1,2,3,4,4a,5,8,8a- _{octahydronaphthalene} ; _3-20 cycloolefins; di- and polyolefins such as butadiene, isoprene, 4-methyl-1,3-pentadiene, 1,3-pentadiene, 1,4-pentadiene, 1,5-hexadiene, 1,4-hexadiene, 1,3-hexadiene, 1,3-octadiene, 1,4-octadiene, 1,5-octadiene, 1,6-octadiene, 1,7-octadiene, ethylidenenorbornene, vinylnorbornene, dicyclopentadiene, 7-methyl-1,6-octadiene, 4-ethylidene-8-methyl-1,7-nonadiene, and 5,9-dimethyl-1,4,8-decatriene; and 3-phenylpropene, 4-phenylpropene, 1,2-difluoroethylene, tetrafluoroethylene, and 3,3,3-trifluoro-1-propene.

In one embodiment, the ethylene/α-olefin block copolymers have a density in the range of 0.866 to 0.89 g/cm ³ , or 0.87 to 0.89 g/cm ³ , or 0.87 to 0.88 g/cm ³ . All individual values and subranges from 0.886 to 0.887 g/cm ³ are included and disclosed herein. The densities disclosed herein for the ethylene/α-olefin block copolymers are determined according to ASTM D-792.

In one embodiment, the ethylene/α-olefin block copolymer has a Mooney viscosity (ML(1+4)@121°C) of 4 to 20, or 8 to 20, or 12 to 20. The Mooney viscosity of the ethylene/α-olefin copolymer is the viscosity of the base polymer (the calculated viscosity of the neat polymer versus a polymer containing a filler such as carbon black).

In one embodiment, the ethylene/α-olefin block copolymers have a melt index (MI or _I2 ) from 1 to 15, or from 1 to 10, or from 1 to 5 g/10 minutes. All individual values and subranges from 1 to 15 g/10 minutes are included and disclosed herein. The melt index, or _I2 , of the ethylene/α-olefin block copolymers is determined according to ASTM D1238 at 190° C., 2.16 kg.

In one embodiment, the ethylene/α-olefin block copolymer excludes styrene.

In one embodiment, the ethylene/α-olefin block copolymer comprises polymerized ethylene and one α-olefin as the only monomer type. In a further embodiment, the α-olefin is selected from propylene, 1-butene, 1-hexene, or 1-octene.

In one embodiment, the ethylene/α-olefin block copolymer is an ethylene/octene block copolymer.

Ethylene/α-olefin block copolymers can be produced via a chain shuttling process such as that described in U.S. Pat. No. 7,858,706, which is incorporated herein by reference. In particular, suitable chain shuttle agents and related information are listed in U.S. Pat. No. 7,858,706, column 16, line 39 to column 19, line 44; suitable catalysts are described in column 19, line 45 to column 46, line 19, and suitable cocatalysts are described in column 46, line 20 to column 51, line 28; and the process is particularly described in column 51, line 29 to column 54, line 56. The process is also described, for example, in U.S. Pat. Nos. 7,608,668, 7,893,166, and 7,947,793.

The ethylene/α-olefin block copolymer may include a combination or two or more of the embodiments described herein.

Fillers The polymeric composition may include one or more fillers. Fillers for use as additives in the present invention include, for example, carbon black; clay; aluminum, magnesium, calcium, sodium, potassium silicates and mixtures thereof; calcium and magnesium carbonates and mixtures thereof; silicon, calcium, zinc, iron, titanium, and aluminum oxides; calcium, barium, and lead sulfates; alumina trihydrate; magnesium hydroxide; phenol-formaldehyde, polystyrene, and poly(alphamethyl)-styrene resins, natural fibers, synthetic fibers, and the like. In one embodiment, the composition may include one or more fillers in an amount of 15 to 40, or 20 to 35, or 25 to 30 weight percent based on the weight of the composition. In one embodiment, the composition includes a carbon black filler.

Additives The polymer composition may include one or more additives. The additives include, but are not limited to, plasticizers, processing oils, vulcanization accelerators, crosslinking agents, antioxidants, antiozonants, peptizers, activators, fatty acids, accelerators, tackifiers, homogenizers, pigments, colorants, flame retardants, UV stabilizers, fungicides, slip agents, etc. In one embodiment, the composition may include less than or equal to 10, or 7.5, or 5.0, or 2.5, or 2.0, or 1.5, or 1.0 weight percent of the total weight of one or more additives based on the weight of the composition.

Plasticizers for use as additives in the present invention include petroleum oils such as aromatic and naphthenic oils, paraffinic oils (as processing oils), polyalkylbenzene oils; organic acid monoesters such as alkyl and alkoxyalkyl oleates and stearates; organic acid diesters such as dialkyl, dialkoxyalkyl, and alkylaryl phthalates, terephthalates, sebacates, adipates, and glutarates; glycol diesters such as tri-, tetra-, and polyethylene glycol dialkanoates; trialkyl trimellitates; trialkyl, trialkoxyalkyl, alkyl diaryl, and triaryl phosphates; chlorinated paraffin oils; coumarone-indene resins; pine tar; vegetable oils such as castor oil, tall oil, rapeseed oil, soybean oil, and their esters and epoxidized derivatives.

Antioxidants and antiozonant additives for use in the present invention include hindered phenols, bisphenols, and thiobisphenols; substituted hydroquinones; tris(alkylphenyl)phosphites; dialkylthiodipropionates; phenylnaphthylamines; substituted diphenylamines; dialkyl, alkylaryl, and diaryl substituted p-phenylenediamines; monomeric and polymeric dihydroquinolines; 2-(4-hydroxy-3,5-t-butylaniline)-4,6-bis(4-hydroxyphenyl)-2,4-diphenylamines; These include s(octylthio)1,3,5-triazine, hexahydro-1,3,5-tris-β-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl-s-triazine, 2,4,6-tris(n-1,4-dimethylpentylphenylenediamine)-1,3,5-triazine, tris-(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate, nickel dibutyldithiocarbamate, 2-mercaptotolylimidazole and its zinc salt, petroleum wax, etc.

Other optional additives for use in the present invention include activators such as metal oxides, such as zinc, calcium, magnesium, cadmium, and lead oxide; fatty acids, such as stearic, lauric, oleic, behenic, and palmitic acids, and the zinc, copper, cadmium, and lead salts thereof; di-, tri-, and polyethylene glycols; and triethanolamine; sulfenamides, such as benzothiazoles, including bisbenzothiazoles, and accelerators, such as thiocarbamylsulfenamides, thiazoles, dithiocarbamates, dithiophosphates, thiurams, guanidines, xanthates, thioureas, and mixtures thereof; adhesion promoters, such as rosin and rosin acids. imparting agents, hydrocarbon resins, aromatic indene resins, phenolic methylene donor resins, phenolic thermosetting resins, alkylphenol formaldehyde resins such as resorcenol-formaldehyde resins, and octylphenol-formaldehyde resins; flame retardants such as metal hydrates such as aluminum trihydroxide and magnesium dihydroxide, or halogenated alkane flame retardants, aromatic halogenated flame retardants, and optionally flame retardant synergists (e.g., metal oxides, halogenated paraffins, triphenyl phosphate, dimethyldiphenylbutane, polycumyl); homogenizers, peptizers, pigments, colorants, UV stabilizers, fungicides, slip agents, and the like.

Vulcanizing agents for use in the present invention include sulfur-containing compounds such as elemental sulfur, 4,4'-dithiodimorpholine, thiuram di- and polysulfides, alkylphenol disulfides, and 2-morpholino-dithiobenzothiazole; peroxides such as di-tert-butyl peroxide, tert-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane, di-(tert-butyl-peroxyisopropyl)benzene, tert-butylperoxybenzoate, and 1,1-di-(tert-butylperoxy)-3,3,5-trimethylcyclohexane; metal oxides such as zinc, magnesium, and lead oxide; dinitroso compounds such as p-quinone-dioxime and p,p'-dibenzoylquinone-dioxime; and phenol-formaldehyde resins containing hydroxymethyl or halomethyl functional groups. The elemental sulfur can be crystalline or amorphous elemental sulfur, either type being in pure form or supported on an inert carrier, an example of supported sulfur being Rhenogran S-80 (80% S and 20% inert carrier) from Rhein Chemie. In one embodiment, sulfur-containing compounds and peroxides are the preferred vulcanizing agents, with sulfur-containing compounds being most preferred. It is understood that mixtures of vulcanizing agents can be used, but this is generally not preferred. The suitability of any of these vulcanizing agents is well known to those skilled in the compounding art. The amount of vulcanizing agent can range from about 1 to 5 weight percent based on the weight of the composition.

Mixing It is understood that the present invention contemplates that the mixing process may occur in successive stages. For example, in one embodiment, a two-stage mastication process may be used in which all ingredients except vulcanizing agents and accelerators are masticated in a first stage, the first stage compound is cooled, the vulcanizing agents and accelerators are added, and then the compound is completed in a second mastication stage. This is done to avoid premature vulcanization caused by masticating at high temperatures in the presence of vulcanizing agents and accelerators. The vulcanization temperatures and times used are conventional. Temperatures ranging from about 121°C to 232°C (250°F to about 440°F) and times ranging from about 1 to about 120 minutes may be utilized.

In one embodiment, the polyisoprene, polybutadiene, and ethylene/α-olefin copolymer, and/or ethylene/α-olefin multiblock copolymer are dry mixed without the addition of extender oil.

In a further embodiment, the polyisoprene, polybutadiene, and ethylene/α-olefin copolymers, and/or ethylene/α-olefin multiblock copolymers are mixed in the presence of aromatic oils, and/or naphthenic oils, and/or paraffinic oils.

In another embodiment, the polyisoprene, polybutadiene, and ethylene/α-olefin copolymer, and/or ethylene/α-olefin multiblock copolymer are premixed prior to the addition of the other ingredients.

The compositions of the present invention can be used to prepare any of a variety of articles or products, or components or portions thereof. By way of example only and without limitation, such articles can be selected from the group consisting of tires and tire sidewalls, sidewall (rubber) inserts, treads, bead fillers, belts, hoses, tubes, gaskets, membranes, moldings, extrusions, automotive parts, and adhesives.

In one embodiment, the composition of the present invention may include at least one additive, such as an additive selected from the group consisting of fillers, fibers, plasticizers, oils, colorants, stabilizers, foaming agents, retarders, accelerators, crosslinkers, and other conventional additives.

The composition can be converted into a finished article by any one of several conventional processes and equipment. Exemplary processes include extrusion, calendaring, injection molding, compression molding, fiber spinning, and other typical thermoplastic processes.

The present invention is particularly useful in the manufacture of tire compounds that include blends of polyisoprene, polybutadiene, and ethylene/α-olefin copolymers, and/or ethylene/α-olefin multiblock copolymers.

In one embodiment, the compositions prepared according to the process of the present invention can be extruded through a die to produce elastomeric articles such as pads for treads, sidewalls, and bead filler components of pneumatic tires, or used to produce sheet stock for air retaining inner liners. In a further embodiment, the compositions prepared according to the present invention can be calendered into woven fabrics or steel cord fabrics to produce cord reinforced sheet stock for tire frameworks and circumferential belt components.

In one embodiment, a "green" or unvulcanized tire is constructed by assembling the various components (except the circumferential belt and tread) on the surface of a cylindrical drum, expanding the assembly radially and compressing it axially to create a toroidal shape, and then positioning and assembling the belt and tread components in the appropriate locations around the toroid. Finally, the green tire is vulcanized by inflating it with high-pressure steam against the inner surface of a sealed, heated aluminum mold. While the various elastomeric compounds are still soft and flowable in the early stages of the vulcanization process, the pressure of the tire against the inner surface of the mold produces the final precise shape, tread pattern, sidewall lettering, and decorative markings. The vulcanization process then causes heat-activated crosslinking reactions to occur within the various elastomeric compounds so that when the mold is finally opened, the compounds are essentially crosslinked to the optimum degree for their intended purpose.

In one embodiment, the vulcanizable composition produced by the process can be molded and vulcanized into an elastomeric article or body. The elastomeric body can be readily CO cured. Thus, the present invention includes a process for interfacial CO curing of molded elastomeric bodies in contact with one another. The process includes (i) forming a vulcanizable elastomeric composition into a molded elastomeric body, (ii) assembling the molded elastomeric body in contact with another molded elastomeric body that includes a majority of highly unsaturated rubber to produce an assembly, and (iii) vulcanizing the assembly under conditions that result in substantial crosslinking across the interface between the molded elastomeric bodies.

In one embodiment, the article can be prepared by injection molding, extrusion, extrusion followed by male or female thermoforming, low pressure molding, compression molding, etc.

A partial, non-exhaustive list of articles that can be made from the compositions of the present invention includes polymer films, fabric covering sheets, polymer sheets, foams, tubes, fibers, coatings, automotive parts such as tires and tire components (such as sidewall inserts), computer parts, building materials, home appliances, power decorations, trash cans, storage or packaging containers, furniture pieces or webbing for use in the garden, parts for lawnmowers, garden hoses and other garden tools, refrigerator gaskets, sound systems, utility cart parts, desk trims, toys, and marine parts. The compositions can also be used in roofing applications, such as roofing applications. The compositions can further be used to make footwear components, such as shafts for boots, particularly boots for industrial businesses. Those skilled in the art can easily expand this list without undue experimentation.

DEFINITIONS Unless stated to the contrary, implicit from the context, or customary in the art, all parts and percentages are by weight and all test methods are current as of the filing date of this disclosure.

The term "blend" or "polymer blend," as used herein, means an intimate physical mixture (i.e., without reaction) of two or more polymers. A blend may or may not be miscible (not phase separated at the molecular level). A blend may or may not be phase separated. A blend may or may not contain one or more domain configurations as determined from transmission electron spectroscopy, light scattering, x-ray scattering, and other methods known in the art. A blend may be achieved by physically mixing two or more polymers at a macro level (e.g., melt blending resins or compounding) or at a micro level (e.g., co-molding in the same reactor).

As used herein, the term "composition" includes mixtures of materials, including compositions and reaction products and decomposition products formed from the materials of the composition. Typically, any reaction products and/or decomposition products are present in trace amounts.

"Crosslinked" and similar terms generally mean that the polymer, in the form of a molded or article, has a xylene extractables of 30% or less by weight (i.e., a gel content of 70% or more by weight), preferably 20% or less by weight (i.e., a gel content of 80% or more by weight), and more preferably 10% or less by weight (i.e., a gel content of 90% or more by weight). Xylene extractables (and gel content) are determined in accordance with ASTM D-2765.

As used herein, the term "polymer" refers to a polymeric compound prepared by polymerizing monomers, whether of the same or different types. Thus, the general term polymer encompasses the terms homopolymer (used to refer to a polymer prepared from only one type of monomer, with the understanding that trace amounts of impurities may be incorporated into the polymer structure), trace amounts of impurities may be incorporated into the polymer and/or polymer, and interpolymer, as defined herein below.

As used herein, the term "interpolymer" refers to a polymer prepared by the polymerization of at least two different types of monomers. The generic term interpolymer includes copolymers (used to refer to polymers prepared from two different types of monomers) and polymers prepared from three or more different types of monomers.

As used herein, the term "ethylene-based polymer" refers to a polymer that contains at least 50% by weight (based on the total weight of the polymer) or a majority amount of polymerized ethylene monomer, and may optionally contain at least one polymerized comonomer.

As used herein, the term "ethylene/α-olefin interpolymer" refers to an interpolymer that contains, in polymerized form, at least 50 weight percent or a majority amount of ethylene monomer (based on the weight of the interpolymer) and at least one α-olefin. Thus, the term does not include ethylene/α-olefin block copolymers.

As used herein, the term "ethylene/α-olefin copolymer" refers to a copolymer that contains, in polymerized form, at least 50% by weight (based on the weight of the copolymer) or a majority amount of ethylene monomer and one α-olefin as the only two monomer types. The α-olefin is randomly distributed within the copolymer. Thus, the term does not include ethylene/α-olefin block copolymers.

As used herein, the term "propylene-based polymer" refers to a polymer that contains a majority weight percent of polymerized propylene monomer (based on the total weight of the polymer) and may optionally contain at least one polymerized comonomer.

The term "comprising" and its derivatives are not intended to exclude the presence of any additional components, steps, or procedures, whether or not the same are disclosed herein. For the avoidance of any doubt, all compositions claimed using the term "comprising" may include any additional additives, adjuvants, or compounds, whether polymeric or otherwise, unless stated to the contrary. In contrast, the term "consisting essentially of" excludes from the scope of any succeeding recitation any other component, step, or procedure, except those that are not essential to operability. The term "consisting of" excludes any component, step, or procedure not specifically defined or listed.

As used herein, the term "masticate" and similar terms refer to the grinding, crushing and/or size reduction of particles of a polymer blend.

TEST METHODS Melt index, MI or I2 or _I2 , of ethylene-based polymers (uncured) is measured in g/10 min and reported in grams eluted every 10 minutes in accordance with ASTM D-1238 at the 190° C./2.16 kilogram (kg) weight condition, formerly known as "Condition E". A 3-8 g pellet type sample was used to measure the melt index.

The density of the uncured samples was measured according to ASTM D792 and is reported as grams per cubic centimeter (g/cc or g/cm ³ ). To measure the density, cube-shaped uncured samples (10 mm x 10 mm x 10 mm) (1-1.5 g) cut from a rolled sheet of uncured polymer were used.

The Mooney viscosity MV of the polymer components (uncured) was measured as ML(1+4) at 100°C and ML(1+4) at 121°C according to ASTM D1646, unless otherwise specified, using a rotational viscometer, Mooney Viscometer (Alpha Technology) with a preheat time of 1 minute and a rotational running time of 4 minutes. Tests were performed on two disk-shaped polymer samples (uncured) (45 mm diameter x 10 mm thickness (lower) and 45 mm diameter x 10 mm thickness (upper)) cut from a rolled sheet of polymer material.

The Mooney viscosity (final masterbatch, uncured), MV, of the formulations was measured as ML(1+4) at 125°C, unless otherwise specified, according to ASTM D1646 using a rotational viscometer, Mooney Viscometer (from Alpha Technology) with 1 minute preheat time and 4 minutes rotational running time. Tests were performed on two disk-shaped pieces of polymer (uncured), 45 mm diameter x 10 mm thick (lower) and 45 mm diameter x 10 mm thick (upper) cut from a rolled sheet of polymer material.

Rheology (final masterbatch, uncured formulation) was measured using an MDR2000™ moving rheometer (Alpha Technologies) according to ASTM D5289. Tests were performed at 180°C for 15 minutes and 140°C for 120 minutes. Tests were performed using disk-shaped samples (uncured) (30 mm diameter x 12.5 mm thickness) cut from a rolled sheet of polymeric material.

Mechanical Properties (final masterbatch, cured)
Shore A hardness (final masterbatch, cured) was measured according to ASTM D2240-05 using a Teclock durometer, Model GS-702N. Tests were performed in triplicate (3 samples) on a 3-ply stack of dumbbell specimens cut from rolled sheets with an average thickness of 2 mm. The total thickness of the test specimens was 6 mm (2 mm x 3 sheets). The specimens were cured by compression molding at 160°C and a pressure of 102 kg/ ^cm2 for 15 minutes. The dimensions of each dumbbell specimen were 2 mm thick, 115 mm long, 33 mm central narrow length, 25 mm end width, and 6 mm central narrow width.

Elongation at break (%) (final masterbatch, cured) is measured according to ASTM D412-98. Tests were performed in triplicate (3 samples) on dumbbell specimens cut from rolled sheets with an average thickness of 2 mm and cured by hot compression molding at 160°C and 102 kg/ ^cm2 pressure for 15 minutes. The dimensions of the dumbbell specimens were 2 mm thick, 115 mm long, 33 mm central narrow length, 25 mm end width, and 6 mm central narrow width. Tests were performed on a Universal Testing System (Model 3365) from Instron (Norwood, MA).

The tensile modulus at 50% strain (kg/ ^cm2 ) (final masterbatch, cured) was measured according to ASTM D412-98 using a Universal Testing System (Model 3365) from Instron (Norwood, MA). Tests were performed in triplicate (3 samples) on dumbbell specimens cut from rolled sheets with an average thickness of 2 mm and cured by hot compression molding at 160°C and 102 kg/ ^cm2 pressure for 15 minutes. The dimensions of the dumbbell specimens were 2 mm thick, 115 mm long, 33 mm central narrow length, 25 mm end width, and 6 mm central narrow width.

Tensile strength (kg/ ^cm2 ) (final masterbatch, cured) was measured according to ASTM D412-98 at room temperature (23°C) and an extension rate of 50 mm/min using a Universal Testing System (Model 3365) from Instron (Norwood, MA). Tests were performed in triplicate on three dumbbell specimens cut from rolled sheets and cured by hot compression molding at 160°C and 102 kg/ ^cm2 pressure for 15 minutes. The dimensions of the dumbbell specimens were 2 mm thick, 115 mm long, 33 mm central narrow length, 25 mm end width, and 6 mm central narrow width.

Heat generation (thermal build-up) (delta temperature, °C) (final masterbatch, cured) was measured according to ASTM D623-07 using a Goodrich Flexometer (Model FT-1100, manufacturer: Ueshiba Seisakusho). The test specimens are in cylindrical shape (diameter 17.8 mm, height 25 mm). First, the specimens are cut from the uncured rolled sheet and cured at 160 °C and 102 kg/ ^cm2 pressure for 25 minutes. A compressive load is applied to the test specimens. Additional cyclic compression was continuously applied to the rubber test specimens for 30 minutes at 1700 rpm. The initial temperature was 50 ^° C and the final temperature was measured by a thermocouple placed at the lower anvil. The delta temperature with continuous deformation was measured according to the following formula:
where _Tinitial is the initial temperature and _Tfinal is the final temperature of the sample after cyclic compression.

The following examples are not intended to, expressly or impliedly, limit the invention. All parts and percentages are by weight unless otherwise stated.

Experimental The materials used in this study are shown in Tables 1A and 1B.

Each formulation included rubber, e.g., natural rubber (STR-20), and butadiene rubber (KBR 01), and polyolefin elastomer, e.g., (POE) (ENGAGE) and/or olefin block copolymer (OBC) (INFUSE). 2,2'-Dibenzamido-diphenyl-disulfide (DBD) with activator additive and jointing agent (RENACIT 4) was used as a peptizer. Carbon black (N550) was used as a filler for reinforcing effect. Zinc oxide (ZnO) and stearic acid were used as activators, and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6-PPD) and 2,2,4-trimethyl-1,2-dihydroquinoline (RD) were used as antioxidants. Alkylphenol novolac resin (DYPHENE 8318) was used as a tackifier. In the curing system, insoluble sulfur (80% sulfur and 20% oil treatment) was used as the crosslinking (vulcanizing) agent and N-tert-butyl-2-benzothiazole-sulfenamide (TBBS) was used as the curing accelerator. The formulations/compositions (masterbatches) are shown in Tables 4-6.

For each formulation, the ingredients of the first masterbatch (1 MB) were mixed in a 1.8 liter internal mixer (Farrel Pomini) according to the following procedure.
a) First, natural rubber (NR) was mixed with peptizer (Renecit-4), butadiene rubber (BR), and POE (ENGAGE) or OBC (INFUSE) for 30 seconds.
b) Carbon black (N550) was added to the internal mixer, causing an increase in temperature due to the incorporation of the filler.
c) When the temperature reached 115 ^° C., zinc oxide (ZnO) and alkylphenol novolac resin (Dyphene 8318) were added.
d) When the temperature reached 125 ^° C., the stearic acid, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, and 2,2,4-trimethyl-1,2-dihydroquinoline were added to the mixer.
e) At 150 ^° C., the resulting mixture was discharged.
f) After discharging, the mixture was sheeted using a two roll mill (Hyupyoung) at 100 ^° C. for 20 times to form a sheet (thickness about 2.5 mm).

The procedure for preparing the first master batch (1MB) is summarized in Table 2.

The first master batch (1MB) was stored in sheet form at room temperature for 24 hours to reduce the temperature of the samples. The material of the first master batch (1MB) was then mixed with insoluble sulfur and an accelerator, TBBS (N-tert-butyl-2-benzothiazole-sulfonamide) in an internal mixer to form the final master batch (FMB) which was discharged at 105 ^° C. and further described in Table 3. After discharge, the FMB material was sheeted ten (10) times (approximately 2.5 mm thick) using a two-roll mill at 100° C.

Compression molding: Shore A hardness test specimens and tensile strength tests were prepared by compressing the final master batch (FMB) material in a compression molding machine at 160°C and 102 kg/ ^cm2 pressure for 15 minutes. Dumbbell-shaped test specimens were cut from the compressed sheets (average thickness 2 mm) and cured at 160°C for 25 minutes under 102 kg/ ^cm2 pressure. The dimensions of the dumbbell-shaped test specimens were 2 mm thick, 115 mm long, 33 mm central narrow length, 25 mm end width, and 6 mm central narrow width.

Comparative formulations (Comparative AC) of POE or OBC/NR density ratios are shown in Table 4 along with Examples 1-4.

Example B (made with Engage 8842) had a POE/NR density ratio of 0.93 and a hardness value of 67, which did not result in a significant increase in the reinforcing effect of the tire sidewall insert compared to control Example A (no ethylene-based copolymer component) which had a hardness value of 64.

The delta temperature from the heat buildup test is an important property for tires, with an upper limit of 50°C. At higher levels of delta temperature for heat buildup, tire components (e.g., inserts) can easily cause the tire to burst during continuous deformation conditions such as driving. Example C (made with Engage 8540) has a POE/NR density ratio of 0.99 and does not provide the continuous deformation required for run-flat tire applications, as the delta temperature of the material in the heat buildup test was 52°C, demonstrating high capability for heat buildup.

In comparison, Examples 1-4 exhibit higher hardness (71-78) and delta temperatures below 50°C compared to Examples A and B, and exhibit reduced thermal enhancement capabilities compared to Example C (52°C).

Example 1 (made with ENGAGE 8400) has a POE Mooney Viscosity/NR Melt Index ratio of 2 and shows a 3 point reduction in Mooney Viscosity compared to Control Example A (no ethylene-based copolymer), which makes the extrusion process difficult to control. In the case of Example 1, the Shore Hardness A (71) and heat buildup (32.6°C) are sufficient for this formulation, but the Mooney Viscosity (40) was too low to handle the material for the extrusion process.

Example C (made with ENGAGE 8540) has a POE Mooney Viscosity/NR Melt Index ratio of 150, with an increased Mooney Viscosity (MV) (74) compared to Control Example A (no ethylene-based copolymer) (MV of 55) and a corresponding decrease in tensile strength from 144 (Example A) to 124 kgf/ ^cm2 . For Examples 2-4, the tensile strength is similar to Control Example A, the POE Mooney Viscosity/NR Melt Index ratio is in the range of 12-60, and the Mooney Viscosity of the compounds is in the range of 45-50, which is acceptable for extrusion processing.

When the POE/NR or OBC/NR weight ratio was below 0.481, as in Examples 2 and 4-6, the delta temperature due to heat build-up was below 50° C., in the range of 28.8-46.3° C. However, when the POE/NR or OBC/NR weight ratio was above 0.825, as in Examples E and F, the delta temperature was above 50° C. (i.e., 56.2 and 51.7° C., respectively), indicating a high capacity for heat build-up and not providing the continuous deformation or acceptable levels of durability required in run-flat tire applications.
The present application also relates to the following aspects:
(1) A composition comprising at least
A) natural rubber having a density of 0.90 to 0.93 g/cm3 ^and a Mooney viscosity (ML(1+4)@100°C) of 50 to 90;
B) a butadiene rubber having a density of 0.90 to 0.93 g/cm3 and a Mooney viscosity (ML(1+4)@100°C) of 40 to 110 ^;
C)
i) ethylene/α-olefin copolymers having a density of 0.870 to 0.902, a Mooney viscosity (ML(1+4)@121°C) of 2 to 23;
ii) an ethylene/α-olefin multiblock copolymer having a density of 0.866 to 0.887, a Mooney viscosity (ML(1+4)@121° C.) of 4 to 20, or
and iii) at least one ethylene-based polymer selected from a combination of i) and ii).
(2) The composition according to (1) above, wherein the ethylene/α-olefin copolymer has a melt index (I ₂ ) of 1 to 30 g/10 min, and/or the ethylene/α-olefin multi-block copolymer has a melt index (I ₂ ) of 1 to 15 g/10 min.
(3) The composition according to (1) or (2) above, wherein the ratio of the density of component C to that of component A is 0.94 to 1.00.
(4) The composition according to any one of (1) to (3) above, wherein the ratio of the Mooney viscosity of component A to the melt index of component C is 12 to 60.
(5) The composition according to any one of the above (1) to (4), wherein component C is i) an ethylene/α-olefin copolymer, and the weight ratio of component C to component A is 0.22 to 0.64.
(6) The composition according to any one of (1) to (5) above, wherein component C is ii) an ethylene/α-olefin multiblock copolymer, and the weight ratio of component C to component A is 0.20 to 0.50.
(7) The composition according to any one of (1) to (6) above, comprising a total amount of components A, B, and C of at least 80% by weight, based on the total weight of the composition.
(8) The composition according to any one of (1) to (7) above, comprising less than 1% by weight of an ethylene/α-olefin/diene (EAODM) interpolymer.
(9) A crosslinked composition formed from the composition according to any one of (1) to (8) above.
(10) An article comprising at least one component formed from the composition according to any one of (1) to (9) above.

Claims (10)

A composition comprising at least
A) natural rubber having a density of 0.90 to 0.93 g/ ^cm3 and a Mooney viscosity (ML(1+4)@100°C) of 50 to 90;
B) a butadiene rubber having a density of 0.90 to 0.93 g/ ^cm3 and a Mooney viscosity (ML(1+4)@100°C) of 40 to 110;
C)
i) ethylene/α-olefin copolymers having a density of 0.870 to 0.902 g/ ^cm3 , a Mooney viscosity (ML(1+4)@121°C) of 2 to 23;
ii) an ethylene/α-olefin multi-block copolymer having a density of 0.866 to 0.887 g/ ^cm3 , a Mooney viscosity (ML(1+4)@121°C) of 4 to 20, or iii) at least one ethylene-based polymer selected from i) and ii),
The weight ratio of component C to component A is 0.825 or less;
Composition. 2. The composition of claim 1, wherein the ethylene/α-olefin copolymer has a melt index (I ₂ ) of 1 to 30 g/10 min (190° C./2.16 kg) and/or the ethylene/α-olefin multi-block copolymer has a melt index (I ₂ ) of 1 to 15 g/10 min (190° C./2.16 kg). The composition according to claim 1 or 2, wherein the ratio of density of component C to component A is 0.94 to 1.00. The composition according to any of claims 1 to 3, wherein the ratio of the Mooney viscosity of component A to the melt index of component C is from 12 to 60, and the melt index ( _I2 ) (g/10 min) is determined according to ASTM D1238 at 190°C and 2.16 kg. The composition according to any one of claims 1 to 4, wherein component C is i) an ethylene/α-olefin copolymer, and the weight ratio of component C to component A is 0.22 to 0.64. The composition according to any one of claims 1 to 4 , wherein component C is ii) an ethylene/α-olefin multiblock copolymer, and the weight ratio of component C to component A is from 0.20 to 0.50. The composition according to any one of claims 1 to 6, comprising a total amount of components A, B, and C of at least 80% by weight, based on the total weight of the composition. The composition of any one of claims 1 to 7, comprising less than 1 wt% ethylene/α-olefin/diene (EAODM) interpolymer. A crosslinked composition formed from the composition according to any one of claims 1 to 8. An article comprising at least one component formed from the composition of any one of claims 1-8.